Control of wound closure and fluid removal management in wound therapy

ABSTRACT

Embodiments of negative pressure wound therapy systems and methods for operating the systems are disclosed. In one embodiment, a negative pressure source can provide negative pressure via a fluid flow path to a wound dressing comprising a stabilizing structure. The stabilizing structure can be inserted into a wound and collapse upon application of negative pressure to the wound when the stabilizing structure is positioned in the wound. A controller can in turn determine a measure of collapse of the stabilizing structure from a pressure in the fluid flow path while the negative pressure source maintains a magnitude of the pressure in the fluid flow path within a negative pressure range. The controller can output an indication responsive to the measure of collapse.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national stage application of InternationalPatent Application No. PCT/US2018/037165, filed Jun. 12, 2018, whichclaims priority to U.S. Provisional Application No. 62/519,790, filedJun. 14, 2017; the disclosures of which are hereby incorporated byreference in their entirety.

BACKGROUND

Embodiments of the present disclosure relate to methods and apparatusesfor dressing and providing therapy to a wound. In particular, butwithout limitation, embodiments disclosed herein relate to negativepressure therapy devices, methods for controlling the operation oftopical negative pressure (TNP) systems, and methods of using TNPsystems.

SUMMARY

In some embodiments, a wound therapy apparatus is disclosed. The woundtherapy apparatus includes: a negative pressure source configured toprovide negative pressure via a fluid flow path to a wound dressingcomprising a stabilizing structure, the stabilizing structure beingconfigured to be inserted into a wound and collapse upon application ofnegative pressure to the wound when the stabilizing structure ispositioned in the wound; a sensor configured to detect pressure in thefluid flow path; and a controller. The controller is configured to:determine a measure of collapse of the stabilizing structure from thepressure in the fluid flow path while the negative pressure sourcemaintains a magnitude of the pressure in the fluid flow path within anegative pressure range, and output an indication responsive to themeasure of collapse.

The wound therapy apparatus of the preceding paragraph can include oneor more of the following features: The controller is configured todetermine the measure of collapse from a change in the magnitude of thepressure in the fluid flow path over time. The controller is furtherconfigured to determine the measure of collapse from a comparison of themagnitude of the pressure in the fluid flow path over time to a pressurechange pattern. The pressure change pattern is indicative of one or moreof: (i) pressure magnitude in the fluid flow path when the stabilizingstructure is fully collapsed, (ii) pressure magnitude in the fluid flowpath when the stabilizing structure is partially collapsed, or (iii)pressure magnitude in the fluid flow path when the stabilizing structureis not collapsed. The measure of collapse comprises a rate of collapseof the stabilizing structure. The controller is further configured todetect that a suture burst or failed from the pressure in the fluid flowpath, the suture being proximate to the wound dressing. The controlleris configured to output the indication to (i) activate or deactivate thenegative pressure source, (ii) activate or deactivate an alarm, (iii)increase or decrease a target negative pressure provided by the negativepressure source, or (iv) release negative pressure in the fluid flowpath. The controller is configured to output the indication to controlactivation and deactivation of the negative pressure source for a timeperiod according to a target level of collapse of the stabilizingstructure rather than to control activation and deactivation of thenegative pressure source to adjust the magnitude of the pressure in thefluid flow path to target a predetermined negative pressure threshold.The time period is at least 1 minutes, 5 minutes, 10 minutes, 30minutes, 1 hour, or 5 hours. The controller is configured to output theindication for presentation to a user or storage in a memory device. Thecontroller is further configured to store, in a memory device, deviceusage data in association with the indication, and the device usage datacomprises one or more of a pressure level, an alarm, an exudate level,an event log, and an operation use time. The controller is furtherconfigured to determine whether the wound dressing comprises thestabilizing structure from the pressure in the fluid flow path. Thesensor is configured to detect the pressure in the fluid flow path atthe wound dressing, in one or more lumens of the fluid flow path, or atan inlet of the negative pressure source. The negative pressure sourceis configured to perform negative pressure therapy when the magnitude ofthe pressure in the fluid flow path is maintained within the negativepressure range.

In some embodiments, a method of operating a wound therapy apparatuscomprising a controller and a negative pressure source is disclosed. Thenegative pressure source is configured to provide negative pressure viaa fluid flow path to a wound dressing, the wound dressing comprising astabilizing structure, the stabilizing structure configured to beinserted into a wound and further configured to collapse uponapplication of negative pressure to the wound when the stabilizingstructure is positioned in the wound. The method includes: monitoringpressure in the fluid flow path; determining a measure of collapse ofthe stabilizing structure from the pressure in the fluid flow path whilethe negative pressure source maintains a magnitude of the pressure inthe fluid flow path within a negative pressure range; and outputting anindication responsive to the measure of collapse. The method isperformed by the controller.

The method of the preceding paragraph can include one or more of thefollowing features: The determining the measure of collapse comprisesdetermining the measure of collapse from a change in the magnitude ofthe pressure in the fluid flow path over time. The determining themeasure of collapse comprises determining the measure of collapse from acomparison of the magnitude of the pressure in the fluid flow path overtime to a pressure change pattern. The pressure change pattern isindicative of one or more of: (i) pressure magnitude in the fluid flowpath when the stabilizing structure is fully collapsed, (ii) pressuremagnitude in the fluid flow path when the stabilizing structure ispartially collapsed, or (iii) pressure magnitude in the fluid flow pathwhen the stabilizing structure is not collapsed. The measure of collapsecomprises a rate of collapse of the stabilizing structure. Theoutputting the indication comprises outputting the indication to (i)activate or deactivate the negative pressure source, (ii) activate ordeactivate an alarm, (iii) increase or decrease a target negativepressure provided by the negative pressure source, or (iv) releasenegative pressure in the fluid flow path. The outputting the indicationcomprises outputting the indication to control activation anddeactivation of the negative pressure source for a time period accordingto a target level of collapse of the stabilizing structure rather thanto control activation and deactivation of the negative pressure sourceto adjust the magnitude of pressure to target a predetermined negativepressure threshold. The time period is at least 1 minutes, 5 minutes, 10minutes, 30 minutes, 1 hour, or 5 hours. The outputting the indicationcomprises outputting the indication for presentation to a user orstorage in a memory device. The method can further include storing, in amemory device, device usage data in association with the indication, andthe device usage data comprises one or more of a pressure level, analarm, an exudate level, an event log, and an operation use time. Themethod can further include determining whether the wound dressingcomprises the stabilizing structure from the pressure in the fluid flowpath. The monitoring the pressure in the fluid flow path comprisesmonitoring the pressure in the fluid flow path at the wound dressing, inone or more lumens of the fluid flow path, or at an inlet of thenegative pressure source. The negative pressure source is configured toperform negative pressure therapy when a magnitude of the pressure inthe fluid flow path is maintained within the negative pressure range.

In some embodiments, a wound therapy apparatus is disclosed. The woundtherapy apparatus includes: a wound dressing comprising a stabilizingstructure configured to be inserted into a wound; a negative pressuresource configured to provide negative pressure via a fluid flow path tothe wound dressing; and a controller. The controller is configured to:monitor a rate of fluid removal from the wound and wirelesslycommunicate the rate of fluid removal to a remote device, and output anindication when the rate of fluid removal meets a threshold.

The wound therapy apparatus of the preceding paragraph can include oneor more of the following features: The controller is further configuredto cause the negative pressure source to adjust a level of negativepressure provided to the wound dressing when the rate of fluid removalmeets the threshold. The controller is further configured to monitor therate of fluid removal from a weight of fluid aspirated from the wound.The controller is further configured to monitor the weight of fluidaspirated from the wound and a weight of fluid stored in a canister. Thewound therapy apparatus can further include a pressure sensor configuredto monitor one or more characteristics of pressure in the fluid flowpath, and wherein the controller is further configured to monitor therate of fluid removal using the one or more characteristics of pressure.The wound therapy apparatus can further include a canister configured tostore fluid removed from the wound, and wherein the controller isfurther configured to monitor the rate of fluid removal from a level offluid in the canister. The controller is further configured to monitorthe level of fluid in the canister using one or more characteristics ofpressure in the fluid flow path. The controller is further configured tomonitor the level of fluid in the canister from an activity level of thenegative pressure source. The negative pressure source comprises avacuum pump, and the activity level of the negative pressure sourcecorresponds to a speed of the vacuum pump. The one or morecharacteristics of pressure comprises a magnitude of pressure signals,and the magnitude of pressure signals increases as the level of fluid inthe canister increases. The controller is further configured towirelessly communicate the rate of fluid removal to the remote device tocause the remote device to store the rate of fluid removal in anelectronic medical record associated with the patient.

In some embodiments, a method of operating a negative pressure woundtherapy apparatus comprising a controller and a negative pressure sourceis disclosed. The negative pressure source is configured to providenegative pressure via a fluid flow path to a wound dressing, the wounddressing comprising a stabilizing structure inserted into a wound. Themethod includes: monitoring a rate of fluid removal from the wound;wirelessly communicating the rate of fluid removal to a remote device;and outputting an indication when the rate of fluid removal meets athreshold. The method is performed by the controller.

The method of the preceding paragraph can include one or more of thefollowing features: The method further includes adjusting a level ofnegative pressure provided by the negative pressure source to the wounddressing when the rate of fluid removal meets the threshold. Themonitoring the rate of fluid removal comprises monitoring the rate offluid removal from a weight of fluid aspirated from the wound. Themonitoring the rate of fluid removal comprises monitoring the weight offluid aspirated from the wound and a weight of fluid absorbed by thewound dressing or stored in a canister. The method further includesmonitoring one or more characteristics of pressure in the fluid flowpath, and wherein the monitoring the rate of fluid removal comprisesmonitoring the rate of fluid removal using the one or morecharacteristics of pressure. The monitoring the rate of fluid removalcomprises monitoring the rate of fluid removal from a level of fluid ina canister that stores fluid removed from the wound. The monitoring therate of fluid removal comprises monitoring the level of fluid in thecanister using one or more characteristics of pressure in the fluid flowpath. The monitoring the rate of fluid removal comprises monitoring thelevel of fluid in the canister from an activity level of the negativepressure source. The negative pressure source comprises a vacuum pump,and the activity level of the negative pressure source corresponds to aspeed of the vacuum pump. The one or more characteristics of pressurecomprises a magnitude of pressure signals, and wherein the magnitude ofpressure signals increases as the level of fluid in the canisterincreases. The wirelessly communicating the rate of fluid removalcomprises wirelessly communicating the rate of fluid removal to theremote device to cause the remote device to store the rate of fluidremoval in an electronic medical record associated with the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present disclosure will be apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings of which:

FIGS. 1, 2, and 3 illustrate embodiments of a negative pressuretreatment system.

FIGS. 4A, 4B, and 4C illustrate multiple views of embodiments of astabilizing structure.

FIG. 5 illustrates a fluid removal management process according to someembodiments.

FIG. 6 illustrates a collapse monitoring process according to someembodiments.

FIG. 7 illustrates a graph of pressure signals according to someembodiments.

DETAILED DESCRIPTION Introduction

The present disclosure relates to methods and apparatuses for dressingand treating a wound with reduced pressure therapy or topical negativepressure (TNP) therapy, as well positive pressure therapy or wound carethat is not aided by applied pressure. In particular, but withoutlimitation, embodiments of this disclosure relate to negative pressuretherapy apparatuses, methods for controlling the operation of TNPsystems, and methods of using TNP systems. The methods and apparatusescan incorporate or implement any combination of the features describedbelow.

The apparatuses and components including the wound overlay and packingmaterials, if any, are sometimes collectively referred to herein aswound dressings.

It will be appreciated that throughout this specification reference ismade to a wound. It is to be understood that the term wound is to bebroadly construed and encompasses open and closed wounds in which skinis torn, cut or punctured or where trauma causes a contusion, or anyother superficial or other conditions or imperfections on the skin of apatient or otherwise that benefit from reduced pressure treatment. Awound is thus broadly defined as any damaged region of tissue wherefluid may or may not be produced. Examples of such wounds include, butare not limited to, abdominal wounds or other large or incisionalwounds, either as a result of surgery, trauma, sterniotomies,fasciotomies, or other conditions, dehisced wounds, acute wounds,chronic wounds, subacute and dehisced wounds, traumatic wounds, flapsand skin grafts, lacerations, abrasions, contusions, burns, electricalburns, diabetic ulcers, pressure ulcers, stoma, surgical wounds, traumaand venous ulcers or the like.

As is used in this section or elsewhere in this specification, reducedor negative pressure levels, such as −X mmHg, represent pressure levelsthat are below atmospheric pressure, which typically corresponds to 760mmHg (or 1 atm, 29.93 inHg, 101.325 kPa, 14.696 psi, etc.). Accordingly,a negative pressure value of −X mmHg reflects pressure that is X mmHgbelow atmospheric pressure, such as a pressure of (760−X) mmHg. Inaddition, negative pressure that is “less” or “smaller” than −X mmHgcorresponds to pressure that is closer to atmospheric pressure (e.g.,−40 mmHg is less than −60 mmHg). Negative pressure that is “more” or“greater” than −X mmHg corresponds to pressure that is further fromatmospheric pressure (e.g., −80 mmHg is more than −60 mmHg).

Although one or more features described herein may be discussed in thecontext of negative pressure wound therapy, the one or more features canapply to other contexts like positive pressure wound therapy ortraditional wound therapy without application of pressure.

Overview

During treatment of a patient's wound using a TNP apparatus, the TNPapparatus may remove fluids including wound exudate from the wound. Tohelp ensure that fluid removal from the wound remains within acceptableperformance limits for the TNP apparatus and acceptable health orcomfort limits for the patient, the TNP apparatus can include acontroller that automatically monitors and tracks a volume or rate offluid removal from the wound, such as a total volume of fluid removal,an instantaneous rate of fluid removal, or a rate of fluid removal pertime period (such as over a last five or last one hour). The controllercan use one or more sensors to monitor the volume or rate of fluidremoval, communicate data to another device, control operation of theTNP apparatus, or provide an indication to a user of the TNP apparatusresponsive to the volume or rate of fluid removal.

The one or more sensors used by the controller to monitor the volume orrate of fluid removal can, for example, include a scale, a level sensor,a pressure sensor, or an activity sensor. The scale can measure a weightof fluid removed from the wound, for instance, by weighing a canister ora wound dressing (which can also be or include any of the wound closuredevices described herein) that collects and stores fluid removal fromthe wound. Because the weight of removed fluid can be generallyproportional to the volume of fluid removal, the controller can use theweight to monitor the volume or rate of fluid removal. The fluid levelsensor can measure a level of fluid in a canister (or wound dressing)which collects and stores fluid removed from the wound. The level offluid in the canister (or wound dressing) can be generally proportionalto the volume of removed fluid and thus can be used by the controller tomonitor the volume or rate of fluid removal. The pressure sensor canmeasure pressure in a fluid flow path through which the TNP apparatusprovides negative pressure to the wound. The controller, in suchimplementations, can analyze one or more characteristics of pressure inthe fluid flow path, such as magnitude of pressure pulses, to determineand monitor the volume or rate of fluid removal. The activity sensor canmeasure a level of activity of the TNP apparatus, such as a speed of anegative pressure source actuator (such as a motor) of the TNPapparatus, and the controller can use the level of activity to determineand monitor the volume or rate of fluid removal.

The controller can store in a memory device one or more valuesindicative of the volume or rate of fluid removal over time foradditional processing. In one example, the controller may then manuallyin response to user input or automatically transmit the one or morevalues using a transmitter of the TNP apparatus to a remote device. Thecontroller can, for instance, transmit via a wireless communicationnetwork the one or more values in a message that upon receipt by theremote device causes the remote device to store the one or more valuesin an electronic medical record associated with a user of the TNPapparatus or an individual prescribed to use the TNP apparatus. Inanother example, the controller can provide a notification (such asoutput an alarm) when the volume or rate of fluid removal meets athreshold that indicates an excess fluid removal or sudden increase ordecrease in fluid removal. In yet another example, the controller canautomatically increase or decrease one or more operational parameters,such as negative pressure provided by the TNP apparatus to the wound,according to the volume or rate of fluid removal.

The controller can moreover utilize information about a patient, such aspatient metabolism or physiology or data from other treatment of thepatient, in combination with the volume or rate of fluid removal tocommunicate data to another device, control operation of the TNPapparatus, or provide an indication to a user of the TNP apparatus. Inone example, the controller can receive information about a volume orrate of fluid that may be provided to the patient (which may includeintravenous fluids, drugs, or painkillers) and use the volume or rate offluid provided to the patient to adjust a threshold used to triggeractivity by the TNP apparatus. It may be particularly important toensure during the first few days of treating a wound that more fluidsare going into a patient than are removed from the wound. Thus, thecontroller can, for instance, compare the volume of fluid provided tothe patient with the volume of fluid removal from the wound and providea notification (such as trigger an alarm) if the volume of fluid removalmeets or exceeds the volume of fluid provided to the patient. Thecontroller can additionally or alternatively automatically adjust one ormore operational parameters, such as the level of negative pressureprovided by the TNP apparatus, to attempt to decrease the rate of fluidremoval from the wound. In another example, the controller can receiveinformation about the metabolism or physiology of the patient and adjusta threshold used to trigger activity by the TNP apparatus responsive tothe volume or rate of fluid removal. The controller, as a result, can bemore sensitive to the volume or rate of fluid removal for certainindividual than other individuals (such as more sensitive to the volumeor rate of fluid removal in smaller individuals than larger individuals)or at certain times than other times (such as when a patient is incritical condition rather than in stable condition).

A wound dressing used in negative wound pressure therapy can include awound matrix or a stabilizing structure configured to collapse whennegative pressure is applied to a wound in which the stabilizingstructure is placed or positioned, as well as when a wound closes andheals. The stabilizing structure can be rigid or substantially rigid.The collapse of the stabilizing structure, however, can be difficult tomonitor once the stabilizing structure is placed in the wound becausethe stabilizing structure may be difficult to see within the wound orthrough a drape, foam, or another wound dressing component placed overthe stabilizing structure.

A TNP apparatus can include a controller that monitors pressure in afluid flow path connecting a source of negative pressure to a wounddressing including a stabilizing structure. The controller canadvantageously, in certain embodiments, monitor a state of collapse ofthe stabilizing structure based on the pressure in the fluid flow path.The stabilizing structure can change negative pressure wound therapydynamics, such as during a continuous or an intermittent operation modeof the TNP apparatus, and the state of collapse of the stabilizingstructure can cause pressure changes, noise, or artifacts, such as dueto a non-homogeneous compression or decompression of the stabilizingstructure. Such pressure artifacts may be detected and analyzed todetermine the state of collapse of the stabilizing structure. Forexample, unlike foam which may become substantially flat when sufficientnegative pressure is applied (such as, −80 mmHg) and may not collapsefurther even when negative pressure is increased, the stabilizingstructure may collapse over a larger range of negative pressures.Collapse of the stabilizing structure can cause variations in thepressure levels, such as pressure artifacts. This may be due to theremoval of air from the cells of the stabilizing structure, which causesits collapse.

The controller can, for example, determine a measure of collapse of thestabilizing structure from the pressure changes in the fluid flow pathand output an indication responsive to the measure of collapse. Thepressure changes can be detected using one or more pressure sensors inthe fluid flow path. The measure of collapse can be determined, forinstance, using one or more of a peak-to-peak magnitude of pressurevariation, a statistical pressure algorithm, a pressure patternmatching, pressure micro-changes like in envelope changes in pressuresignal, or pressure frequency variation, among other approaches. Themeasure of collapse can, in some instances, be a degree or rate ofcollapse of the stabilizing structure and indicative of a degree or rateof closure of the wound.

The controller can monitor the healing of the wound from the measure ofcollapse as the wound closes and heals. The healing or closing of thewound can cause the collapse of the stabilizing structure beyond whatmay be expected when a particular level of negative pressure is appliedto the wound incorporating the stabilizing structure. As a result, thecontroller can determine that a degree or rate of collapse in excess ofthe degree or rate of collapse attributable to application of negativepressure may be attributable to wound healing or closure. In suchimplementations, the indication output by the controller can be outputfor presentation to user and denote to replace the stabilizing structurewith a smaller stabilizing structure that may be more appropriate forthe wound since the wound has partially healed or closed.

The controller can control provision of wound therapy, a degree or rateof collapse of the stabilizing structure, a size of the wound, an amountor rate of fluid removed from the wound, or an amount or rate of painexperienced based on the measure of collapse. For example, thecontroller can, at least for a period of time (like 30 seconds, 1minutes, 2 minutes, 3 minutes, 5 minutes, or 10 minutes) or for a numberof compression or decompression cycles (like 2, 3, 5, 10, 20, or 50,compression-decompression cycles) activate or deactivate a negativepressure source according to the measure of collapse. Moreover, thecontroller can activate or deactivate the negative pressure sourceaccording to the measure of collapse in addition to or instead ofcontrolling the negative pressure source to target a specific level or arange of negative pressure. Such control advantageously can, in certainembodiments, enable provision of therapy to be tailored to a particularwound, environment or patient (such as in a non-linear way), whichthereby can enable faster, less painful, more effective, or moreresponsive therapy. In addition, such control may enable the controllerto be more reactive to or prevent blockages in the fluid flow pathbecause more tailored or customized negative pressure therapy can beapplied based on, for example, measured fluid removal from the wound.For example, more appropriate level (or levels) of negative pressure canbe continuously selected based on the measured fluid removal, which canresult in a lessened risk of a blockage as negative pressure beingapplied in tailored to the rate of flow of removed fluid.

The controller can determine, prior to initiating or reinitiatingprovision of therapy, one or more characteristics of a wound dressingfrom the pressure in the fluid flow path. The one or morecharacteristics can include a size of the wound dressing, a type of thewound dressing, or whether the wound dressing includes a stabilizingstructure. In one example, in response to determining that the wounddressing includes the stabilizing structure, the controller candetermine to control application of negative pressure based on themeasure of collapse, and in response to determining that the wounddressing does not include the stabilizing structure, the controller candetermine to control application of negative pressure instead to apressure setpoint.

The controller can detect or characterize patient movement from pressurevariations in the fluid flow path due to shifts in the stabilizingstructure of a wound dressing. The patient movement can include, forinstance, leg or arm movement or breathing by the patient (for example,when the stabilizing structure is placed in an abdominal wound).

The controller can determine whether a suture burst or failed frompressure variations in the fluid flow path. The suture may be used tohold together tissue near a wound dressing. In one example, thecontroller may monitor cycles of variations in pressure, such as in apeak-to-peak pressure signal, and detect a spike in pressure that may beindicative of a volume change of the wound due to a burst or failedsuture.

Pressure Therapy Systems

FIG. 1 illustrates an embodiment of a negative pressure treatment system100 that comprises a wound packer 102 inserted into a wound 101. Thewound packer 102 may comprise porous materials such as foam, and in someembodiments may comprise one or more embodiments of wound closuredevices described in further detail in this section or elsewhere in thisspecification. In some embodiments, the perimeter or top of any woundclosure device inserted into the wound 101 may also be covered with foamor other porous materials. A single drape 104 or multiple drapes may beplaced over the wound 101, and is preferably adhered or sealed to theskin on the periphery of the wound 101 so as to create a fluid-tightseal. An aperture 106 may be made through the drape 104 which can bemanually made or preformed into the drape 104 so as to provide a fluidicconnection from the wound 101 to a source of negative pressure such as aTNP apparatus 110 that includes a pump. Preferably, the fluidicconnection between the aperture 106 and the pump of the TNP apparatus110 is made via a conduit 108. In some embodiments, the conduit 108 maycomprise a RENASYS® Soft Port™, manufactured by Smith & Nephew. Ofcourse, in some embodiments, the drape 104 may not necessarily comprisean aperture 106, and the fluidic connection to the pump of the TNPapparatus 110 may be made by placing the conduit 108 below the drape. Insome wounds, particularly larger wounds, multiple conduits 108 may beused, fluidically connected via one or more apertures 106.

In some embodiments, the drape 104 may be provided with one or morecorrugations or folds. Preferably, the corrugations are aligned alongthe longitudinal axis of the wound, and as such may support closure ofthe wound by preferentially collapsing in a direction perpendicular tothe longitudinal axis of the wound. Such corrugations may aid in theapplication of contractile forces parallel to the wound surface and inthe direction of wound closure. Examples of such drapes may be found inapplication Ser. No. 12/922,118, titled “Vacuum Closure Device,” filedNov. 17, 2010 (published as US 2011/0054365), which is herebyincorporated by reference in its entirety.

In use, the wound 101 is prepared and cleaned. In some cases, such asabdominal wounds, a non- or minimally-adherent organ protection layer(not illustrated) may be applied over any exposed viscera. The woundpacker 102 is then inserted into the wound, and is covered with thedrape 104 so as to form a fluid-tight seal. A first end of the conduit108 is then placed in fluidic communication with the wound, for examplevia the aperture 106. The second end of the conduit 108 is connected tothe TNP apparatus 110. The pump of the TNP apparatus 110 may then beactivated so as to supply negative pressure to the wound 101 andevacuate wound exudate from the wound 101. As will be described inadditional detail below and in relation to the embodiments of theforegoing wound closure devices, negative pressure may also aid inpromoting closure of the wound 101, for example by approximatingopposing wound margins.

Any structure or component disclosed herein this section or elsewhere inthe specification may comprise a radiopaque material. A radiopaquematerial advantageously allows a clinician to more easily find pieces ofthe wound closure device that may have come loose from the structure andbecome lost in the wound. Some examples of radiopaque materials includebarium sulfate, bismuth trioxide, bismuth subcarbonate, bismuthoxychloride, and tungsten.

FIG. 2 illustrates a negative pressure therapy system 10A according tosome embodiments. The system 10A includes a TNP apparatus 11 (which maybe similar to the TNP apparatus 110 and the TNP apparatus of theOverview section) and a remote data processing system 13. The TNPapparatus 11 can be used to treat a wound using a wound dressing that isin fluidic communication with the TNP apparatus 11 via a fluid flowpath. The TNP apparatus 11 can include a controller 12A (which may besimilar to the controller of the Overview section), a memory device 12B,a negative pressure source 12C, a user interface 12D, a power supply12E, a pressure sensor 12F, a transceiver 12G, and additional sensor(s)12H that are configured to electrically communicate with one another.The TNP apparatus 11 can include a canister 12I that collects fluidincluding wound exudate. In some embodiments, wound exudate canadditionally or alternatively be absorbed by a wound dressing and thecanister 12I then may or may not be used.

The controller 12A can control operations of one or more othercomponents of the TNP apparatus 11 according at least to instructionsstored in the memory device 12B. The controller 12A can, for instance,control operations of and supply of negative pressure by the negativepressure source 12C. The negative pressure source 12C can include apump, such as, without limitation, a rotary diaphragm pump or otherdiaphragm pump, a piezoelectric pump, a peristaltic pump, a piston pump,a rotary vane pump, a liquid ring pump, a scroll pump, a diaphragm pumpoperated by a piezoelectric transducer, a voice coil pump, or any othersuitable pump or micropump or any combinations of the foregoing. Theuser interface 12D can include one or more elements that receive userinputs or provide user outputs to a patient or caregiver. The one ormore elements that receive user inputs can include buttons, switches,dials, touch screens, microphones, or the like. The one or more elementsthat provide user outputs can include lights, displays, speakers, or thelike.

The pressure sensor 12F can be used to monitor pressure underneath awound dressing, such as by monitoring (i) pressure in a fluid flow pathconnecting the negative pressure source 12C and the wound dressing asillustrated by FIG. 3, (ii) pressure at or in the wound dressing, or(iii) pressure at or in the negative pressure source 12C. In someimplementations, the pressure sensor 12F can include at least twopressure sensors that are positioned in or fluidically connected to thefluid flow path to permit differential measurement of the pressure, suchas differential measurement between pressure at or near the wound andpressure at or near the TNP apparatus 11. For example, a first pressuresensor can be positioned upstream of the wound (such as at or near theinlet of the negative pressure source 12C) and a second pressure sensorcan be positioned to detect pressure at or near the wound or at or neara canister. This configuration can be accomplished by incorporating, inaddition to one or more lumens forming a first fluid flow pathconnecting the negative pressure source 12C to the wound, a second fluidflow path that includes one or more lumens connecting the TNP apparatus11 to the wound and through which the second pressure sensor can monitorpressure at or near the wound or at or near a canister. The first andsecond fluid flow paths can be fluidically isolated from each other.

FIG. 3 illustrates a negative pressure therapy system 10B according tosome embodiments. The system 10B includes the TNP apparatus 11, as wellas a fluid flow path 15, a wound dressing 16, and a wound 17. The TNPapparatus 11 can be used to treat the wound 17 using the wound dressing16 that is in fluidic communication with the negative pressure source12C via the fluid flow path 15. The pressure sensor 12F is depicted inFIG. 3 as being positioned in the fluid flow path 15, such as at or nearan inlet of the TNP apparatus 11, to measure pressure in the fluid flowpath 15. The wound dressing 16 can embody any of the wound dressings orwound closure devices described herein. In some implementations, thecanister 12I may not be used and, instead, wound exudate can becollected by wound dressing 16 which can be absorbent. In otherimplementations, both the canister 12I and the wound dressing 16 can beused, and the wound dressing 16 can be absorbent.

Turning again to FIG. 2, the transceiver 12G can be used to communicatewith the data processing system 13 via a network 14. The transceiver 12Gcan, for example, transmit device usage data like alarms, rate of fluidremoval, measured pressure, or changes to a therapy program administeredby the TNP apparatus 11 to the data processing system 13. The network 14can be a communication network, such as a wireless communication networklike a cellular communication network or a wired communication network.The memory device 12B can be used to store the device usage data thatmay then be transmitted by the transceiver 12G. The data processingsystem 13 can, in some implementations, automatically store datareceived from the transceiver 12G to an electronic medical fileassociated with a patient that used or is prescribed to use the TNPapparatus 11. The transceiver 12G can, in some instances, include atransmitter to transmit data separate from a receiver used to receivedata.

The additional sensor(s) 12H can include, for example, a level sensorthat detects a level of fluid in the canister 12I or a scale that weighsone or more components of the negative pressure therapy systems 10A and10B like the canister 12I or the wound dressing 16. The controller 12Acan use the additional sensor(s) 12H to monitor a rate of fluid removalfrom a wound, such as the wound 17.

Stabilizing Structures and Wound Closure Devices

FIGS. 4A, 4B, and 4C illustrate multiple views of embodiments of astabilizing structure 200. The stabilizing structure 200 can collapse inany manner described in this section or elsewhere in this specificationwith or without the application of negative pressure. For example, thestabilizing structure may collapse significantly more in one plane thanin another plane upon application of negative pressure. In someembodiments, the stabilizing structure is configured to collapse more ina horizontal plane parallel to the length and width of the stabilizingstructure than in a vertical plane perpendicular to the horizontalplane. In embodiments, particular rows may collapse in a firstdirection, while another row may collapse in the same or an opposingdirection. In certain embodiments, the stabilizing structure maycollapse along the width of the stabilizing structure while remainingrelatively rigid along the length of the stabilizing structure and inthe vertical direction.

The stabilizing structure may be comprised of any materials described inthis section or elsewhere in this specification, including: flexibleplastics such as silicone, polyurethane, rigid plastics such aspolyvinyl chloride, semi-rigid plastics, semi-flexible plastics,biocompatible materials, composite materials, metals, and foam. Incertain embodiments, the stabilizing structure may comprise a radioopaque material, to more readily allow a clinician to find pieces of thestabilizing structure within the wound.

Further details regarding the wound closure devices, stabilizingstructures, related apparatuses and methods of use that may be combinedwith or incorporated into any of the embodiments described herein arefound elsewhere throughout this specification and in InternationalApplication No. PCT/US2013/050698, filed Jul. 16, 2013, published as WO2014/014922 A1, the entirety of which is hereby incorporated byreference.

Pressure Therapy Methods

FIG. 5 illustrates a fluid removal management process 20 performable bya device, such as the controller 12A of the TNP apparatus 11 or acontroller of the TNP apparatus 110. For convenience, the fluid removalmanagement process 20 is described in the context of the TNP apparatus11 of FIGS. 2 and 3, but may instead be implemented in other systemsdescribed herein or by other computing systems not shown. The fluidremoval management process 20 can advantageously, in certainembodiments, enable the TNP apparatus 11 to monitor a rate of fluidremoval from the wound 17 and automatically wirelessly communicate therate of fluid removal to another device and output an indication whenthe rate of fluid removal becomes excessive.

At block 21, the fluid removal management process 20 can monitor a rateof fluid removal from the wound 17. For example, the fluid removalmanagement process 20 can use measurements provided by one or moresensors, like the pressure sensor 12F or the additional sensor(s) 12H,to monitor the rate of fluid removal.

At block 22, the fluid removal management process 20 can wirelesslycommunicate the rate of fluid removal to the data processing system 13.The fluid removal management process 20 can, for instance, use thetransceiver 12G to communicate the rate of fluid removal via the network14 to the data processing system 13. The fluid removal managementprocess 20 can communicate over a wired interface rather than or inaddition to wirelessly in some implementations.

At block 23, the fluid removal management process 20 can determinewhether the rate of fluid removal meets a threshold. The thresholds canbe a rate threshold whose magnitude indicates an excessive fluid rateincrease or decrease during delivery of negative pressure therapy withthe TNP apparatus 11.

When the rate of fluid removal meets the threshold, at block 24, thefluid removal management process 20 can output an indication that therate of fluid removal experienced an excessive fluid rate increase ordecrease during delivery of negative pressure therapy with the TNPapparatus 11. The indication can, for instance, include activation avisible or audible alarm of the user interface 12D or display of atextual warming message on a display of the user interface 12D.

On the other hand, when the rate of fluid removal does not meet thethreshold, the fluid removal management process 20 can end.

FIG. 6 illustrates a collapse monitoring process 30 performable by adevice, such as the controller 12A of the TNP apparatus 11 or acontroller of the TNP apparatus 110. For convenience, the collapsemonitoring process 30 is described in the context of the TNP apparatus11 of FIGS. 2 and 3, but may instead be implemented in other systemsdescribed herein or by other computing systems not shown. The collapsemonitoring process 30 can advantageously, in certain embodiments, enablethe TNP apparatus 11 to monitor collapse of a stabilizing structure ofthe wound dressing 16 placed in the wound 17 from pressure in the fluidflow path 15 and appropriately control operation of the TNP apparatus11.

At block 31, the collapse monitoring process 30 can monitor pressure ina fluid flow path. For example, the controller 12A can monitor pressureusing the pressure sensor 12F or the additional sensor(s) 12H positionedto detect the pressure in the fluid flow path 15.

At block 32, the collapse monitoring process 30 can determine a measureof collapse of a stabilizing structure of a wound dressing. For example,the controller 12A can determine a measure of collapse of a stabilizingstructure of the wound dressing 16 from the pressure in the fluid flowpath 15 detected by the pressure sensor 12F or the additional sensor(s)12H. The measure of collapse can, for instance, be determined from achange in a magnitude or a frequency of the pressure in the fluid flowpath over time as described herein. In one example, the controller cancompare the magnitude over time to one or more pressure patternsindicative of one of (i) pressure magnitude in the fluid flow path whenthe stabilizing structure is fully collapsed, (ii) pressure magnitude inthe fluid flow path when the stabilizing structure is partiallycollapsed, and (iii) pressure magnitude in the fluid flow path when thestabilizing structure is not collapsed, and the controller can determinethe measure of collapse from a degree of similarity of the magnitudeover time to the one or more of the pressure patterns. In anotherexample, the measure of collapse can be or be related to a degree or arate of collapse of the stabilizing structure.

At block 33, the collapse monitoring process 30 can output an indicationresponsive to the measure of collapse. For example, the controller 12Acan output an indication according to the measure of collapse. Thecollapse monitoring process 30 can, in some implementations, output theindication to control activation and deactivation of the negativepressure source for a time period (such as for 1 minutes, 5 minutes, 10minutes, 30 minutes, 1 hour, or 5 hours) according to the measure ofcollapse rather than to control activation and deactivation of thenegative pressure source to adjust the magnitude of pressure to target apredetermined negative pressure threshold. In some implementations, thecontroller can output the indication for presentation to a user (such asvia a visible, audible, or tactile alarm of the user interface 12D ordisplay of a textual warming message on a display of the user interface12D) or for storage in a memory device, such as for storage inassociation with device usage data like a pressure level, an alarm, anexudate level, an event log, and an operation use time. In someembodiments, at block 33, the collapse monitoring process 30 can adjustone or more parameters of negative pressure therapy, such as thenegative pressure level, mode (for example, continuous or intermittent),etc. Control of negative pressure therapy can be tied to achieving ormaintaining a target level of collapse of the stabilizing structure (forexample, 10% when the treatment has begun, 30% after treatment has beenapplied for some time, etc.). Additionally or alternatively, thecollapse monitoring process 30 can activate or deactivate the negativepressure source, increase or decrease a target negative pressureprovided by the negative pressure source, or release negative pressurein the fluid flow path.

Fluid Detection

Presence of exudate in the fluid flow path can be detected by processingdata from one or more pressure sensors, such as the pressure sensor 12F.This detection can be enhanced by changing one or more settings of thenegative pressure source, such as increasing the delivered vacuum level,decreasing the vacuum level, pausing or stopping the negative pressuresource, changing the speed of an actuator (such as a pump motor),changing a cadence of the actuator, and the like. In some embodiments,as the negative pressure source operates, it generates pressure pulsesor signals that are propagated through the fluid flow path. The pressuresignals are illustrated in the pressure curve 402 of FIG. 7 according tosome embodiments. As is illustrated in region 404, pressure in the fluidflow path varies or oscillates around a particular pressure setting orset point 408 (for example, as selected by the user) during normaloperation of the system. Region 406 illustrates pressure pulses in theflow path when there is a blockage distal to the negative pressuresource, such as the canister (or dressing) becomes full or a canisterfilter is occluded or blocked. As is illustrated, a distal blockagecauses a reduced volume to be seen upstream of the canister (ordressing), and the amplitude of the pressure pulses increases. Thefrequency of a pressure signal is slowed or decreased in someembodiments. In certain embodiments, this change or “bounce” in themagnitude (or frequency) of the pressure pulse signal can be magnifiedor enhanced by varying the speed of the actuator, varying the cadence ofthe actuator, such as by adjusting pulse-width modulation (PWM) controlparameters, and the like. Such adjustments of negative pressure sourceoperation are not required but can be performed over short time durationand the changes can be small such that the operation of the systemremains relatively unaffected. In some embodiments, the canister filtercan be hydrophobic so that the flow of liquid is substantially blockedwhile the flow of air is allowed. Additional details of flow ratedetection are described in U.S. Pat. No. 8,843,327, which isincorporated by reference in its entirety.

Canisterless systems can use an absorbent dressing for exudate removedfrom the wound. Such dressing may include absorbing or superabsorbingmaterial to collect or retain exudate so that it is not aspirated intothe negative pressure source. Similar to a canister filter, a dressingfilter (which may be hydrophobic) may be used to prevent the exudatefrom reaching the negative pressure source. In such systems, detectionof a dressing full condition or dressing filter (which may be) occludedcondition can be an equivalent to detection of a canister fullcondition.

Changes in characteristics of pressure signals can be used to determinerate of fluid removal, distal blockages, level of exudate in thecanister (or dressing), canister (or dressing) full conditions, and thelike. The characteristics can include signal magnitude, frequency, shape(e.g., envelope), etc. In some embodiments, the system can detect therate of fluid removal by monitoring the change in the magnitude ofpressure pulses over time. For example, as the canister (or dressing)becomes filled with wound exudate, the magnitude of pressure pulses canincrease, as illustrated in region 406. Additional details of monitoringthe rate of fluid removal are disclosed in U.S. Patent Publication No.2016/0184496, which is incorporated by reference in its entirety.

Wound Closure and Treatment Methods

The stabilizing structures or wound closure devices described in thissection or elsewhere in this specification may be used in conjunctionwith methods or systems for the closure of a wound. In some embodimentsof methods of use for closure of a wound, one or more of the stabilizingstructures or wound closure devices of any of the embodiments describedin this section or elsewhere in this specification is placed into awound. In some embodiments, an organ protection layer may be provided inthe wound before placement of the stabilizing structure. In certainembodiments, foam or other porous material may be placed in the woundalong with the stabilizing structure or wound closure device, eitherbelow, above, or surrounding the stabilizing structure or wound closuredevice. Foam or other porous material may also surround the perimeter ofthe stabilizing structure or wound closure device.

The stabilizing structure or wound closure device may be configured tocollapse in any manner as described in this section or elsewhere in thisspecification, for example by having a particular size and shape, or bycomprising a certain volume of foam or other porous material within thecells of the structure. The stabilizing structure or wound closuredevice may further be altered in any manner described in this section orelsewhere in this specification so as to better accommodate the shape ofthe wound. After placement in the wound, the stabilizing structure orwound closure device can be sealed by a fluid-tight drape. Thefluid-tight drape can comprise a port configured for the application ofnegative pressure. A source of negative pressure may then be connectedto the port and negative pressure may be applied to the wound. Thestabilizing structure or wound closure device may be replaced over timeby stabilizing structures or wound closure devices of various shapes andsizes as desired to best promote wound healing.

Other Variations

Any value of a threshold, limit, duration, etc. provided herein is notintended to be absolute and, thereby, can be approximate. In addition,any threshold, limit, duration, etc. provided herein can be fixed orvaried either automatically or by a user. Furthermore, as is used hereinrelative terminology such as exceeds, greater than, less than, etc. inrelation to a reference value is intended to also encompass being equalto the reference value. For example, exceeding a reference value that ispositive can encompass being equal to or greater than the referencevalue. In addition, as is used herein relative terminology such asexceeds, greater than, less than, etc. in relation to a reference valueis intended to also encompass an inverse of the disclosed relationship,such as below, less than, greater than, etc. in relations to thereference value. Moreover, although blocks of the various processes maybe described in terms of determining whether a value meets or does notmeet a particular threshold, the blocks can be similarly understood, forexample, in terms of a value (i) being below or above a threshold or(ii) satisfying or not satisfying a threshold.

Features, materials, characteristics, or groups described in conjunctionwith a particular aspect, embodiment, or example are to be understood tobe applicable to any other aspect, embodiment or example describedherein unless incompatible therewith. All of the features disclosed inthis specification (including any accompanying claims, abstract anddrawings), or all of the steps of any method or process so disclosed,may be combined in any combination, except combinations where at leastsome of such features or steps are mutually exclusive. The protection isnot restricted to the details of any foregoing embodiments. Theprotection extends to any novel one, or any novel combination, of thefeatures disclosed in this specification (including any accompanyingclaims, abstract and drawings), or to any novel one, or any novelcombination, of the steps of any method or process so disclosed.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of protection. Indeed, the novel methods and systems describedherein may be embodied in a variety of other forms. Furthermore, variousomissions, substitutions and changes in the form of the methods andsystems described herein may be made. Those skilled in the art willappreciate that in some embodiments, the actual steps taken in theprocesses illustrated or disclosed may differ from those shown in thefigures. Depending on the embodiment, certain of the steps describedabove may be removed, others may be added. For example, the actual stepsor order of steps taken in the disclosed processes may differ from thoseshown in the figure. Depending on the embodiment, certain of the stepsdescribed above may be removed, others may be added. For instance, thevarious components illustrated in the figures may be implemented assoftware or firmware on a processor, controller, ASIC, FPGA, ordedicated hardware. Hardware components, such as processors, ASICs,FPGAs, and the like, can include logic circuitry. Furthermore, thefeatures and attributes of the specific embodiments disclosed above maybe combined in different ways to form additional embodiments, all ofwhich fall within the scope of the present disclosure.

User interface screens illustrated and described herein can includeadditional or alternative components. These components can includemenus, lists, buttons, text boxes, labels, radio buttons, scroll bars,sliders, checkboxes, combo boxes, status bars, dialog boxes, windows,and the like. User interface screens can include additional oralternative information. Components can be arranged, grouped, displayedin any suitable order.

Although the present disclosure includes certain embodiments, examplesand applications, it will be understood by those skilled in the art thatthe present disclosure extends beyond the specifically disclosedembodiments to other alternative embodiments or uses and obviousmodifications and equivalents thereof, including embodiments which donot provide all of the features and advantages set forth herein.Accordingly, the scope of the present disclosure is not intended to belimited by the specific disclosures of preferred embodiments herein, andmay be defined by claims as presented herein or as presented in thefuture.

Conditional language, such as “can,” “could,” “might,” or “may,” unlessspecifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements, or steps. Thus, such conditional language is notgenerally intended to imply that features, elements, or steps are in anyway required for one or more embodiments or that one or more embodimentsnecessarily include logic for deciding, with or without user input orprompting, whether these features, elements, or steps are included orare to be performed in any particular embodiment. The terms“comprising,” “including,” “having,” and the like are synonymous and areused inclusively, in an open-ended fashion, and do not excludeadditional elements, features, acts, operations, and so forth. Also, theterm “or” is used in its inclusive sense (and not in its exclusivesense) so that when used, for example, to connect a list of elements,the term “or” means one, some, or all of the elements in the list.Further, the term “each,” as used herein, in addition to having itsordinary meaning, can mean any subset of a set of elements to which theterm “each” is applied.

Conjunctive language such as the phrase “at least one of X, Y, and Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to convey that an item, term, etc. may beeither X, Y, or Z. Thus, such conjunctive language is not generallyintended to imply that certain embodiments require the presence of atleast one of X, at least one of Y, and at least one of Z.

Language of degree used herein, such as the terms “approximately,”“about,” “generally,” and “substantially” as used herein represent avalue, amount, or characteristic close to the stated value, amount, orcharacteristic that still performs a desired function or achieves adesired result. For example, the terms “approximately”, “about”,“generally,” and “substantially” may refer to an amount that is withinless than 10% of, within less than 5% of, within less than 1% of, withinless than 0.1% of, and within less than 0.01% of the stated amount. Asanother example, in certain embodiments, the terms “generally parallel”and “substantially parallel” refer to a value, amount, or characteristicthat departs from exactly parallel by less than or equal to 15 degrees,10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degree.

The scope of the present disclosure is not intended to be limited by thespecific disclosures of preferred embodiments in this section orelsewhere in this specification, and may be defined by claims aspresented in this section or elsewhere in this specification or aspresented in the future. The language of the claims is to be interpretedbroadly based on the language employed in the claims and not limited tothe examples described in the present specification or during theprosecution of the application, which examples are to be construed asnon-exclusive.

What is claimed is:
 1. A wound therapy apparatus comprising: a wounddressing comprising a stabilizing structure configured to be insertedinto a wound of a patient; a negative pressure source configured toprovide negative pressure via a fluid flow path to wound covered by thewound dressing; a pressure sensor configured to monitor pressure in thefluid flow path; and a controller programmed to: monitor a rate of fluidremoval from the wound during provision of negative pressure by thenegative pressure source by monitoring pressure variations in the fluidflow path based on an output of the pressure sensor, wherein collapse ofthe stabilizing structure as a result of provision of negative pressurecauses changes in pressure in the fluid flow path, wirelesslycommunicate the rate of fluid removal to a remote device, determine thatthe rate of fluid removal causes a volume of fluid being removed fromthe wound of the patient to meet or exceed a volume of fluid beingprovided to the patient, and responsive to the determination, provide anotification that the volume of fluid being removed from the wound ofthe patient meets or exceeds the volume of fluid being provided to thepatient.
 2. The wound therapy apparatus of claim 1, wherein thecontroller is further programmed to monitor the rate of fluid removalfrom a weight of fluid aspirated from the wound.
 3. The wound therapyapparatus of claim 2, wherein the controller is further programmed tomonitor the weight of fluid aspirated from the wound and a weight offluid stored in a canister.
 4. The wound therapy apparatus of claim 1,further comprising a canister configured to store fluid removed from thewound, and wherein the controller is further programmed to monitor therate of fluid removal from a level of fluid in the canister.
 5. Thewound therapy apparatus of claim 4, wherein the controller is furtherprogrammed to monitor the level of fluid in the canister using one ormore characteristics of pressure in the fluid flow path.
 6. The woundtherapy apparatus of claim 4, wherein the controller is furtherprogrammed to monitor the level of fluid in the canister from anactivity level of the negative pressure source.
 7. The wound therapyapparatus of claim 6, wherein the negative pressure source comprises avacuum pump, and the activity level of the negative pressure sourcecorresponds to a speed of the vacuum pump.
 8. The wound therapyapparatus of claim 5, wherein the one or more characteristics ofpressure comprises a magnitude of pressure signals, and the magnitude ofpressure signals increases as the level of fluid in the canisterincreases.
 9. The wound therapy apparatus of claim 1, wherein thecontroller is further programmed to wirelessly communicate the rate offluid removal to the remote device to cause the remote device to storethe rate of fluid removal in an electronic medical record associatedwith a patient.
 10. A method of operating a negative pressure woundtherapy apparatus comprising a controller and a negative pressure sourceconfigured to provide negative pressure via a fluid flow path to a woundof a patient covered by a wound dressing, the wound dressing comprisinga stabilizing structure inserted into the wound, the method comprising:monitoring a rate of fluid removal from the wound during provision ofnegative pressure by monitoring pressure variations in the fluid flowpath, wherein collapse of the stabilizing structure as a result ofprovision of negative pressure causes changes in pressure in the fluidflow path; wirelessly communicating the rate of fluid removal to aremote device; determining that the rate of fluid removal causes avolume of fluid being removed from the wound of the patient to meet orexceed a volume of fluid being provided to the patient; and responsiveto the determination, providing a notification that the volume of fluidbeing removed from the wound of the patient meets or exceeds the volumeof fluid being provided to the patient, wherein the method is performedby the controller.
 11. The method of claim 10, further comprisingdecreasing a level of negative pressure provided by the negativepressure source to the wound dressing responsive to the determination.12. The method of claim 10, wherein said monitoring the rate of fluidremoval comprises monitoring the rate of fluid removal from a weight offluid aspirated from the wound.
 13. The method of claim 12, wherein saidmonitoring the rate of fluid removal comprises monitoring the weight offluid aspirated from the wound and a weight of fluid absorbed by thewound dressing or stored in a canister.
 14. The method of claim 10,further comprising monitoring one or more characteristics of pressure inthe fluid flow path in addition to pressure variation, and wherein saidmonitoring the rate of fluid removal comprises monitoring the rate offluid removal using the one or more characteristics of pressure.
 15. Themethod of claim 10, wherein said monitoring the rate of fluid removalcomprises monitoring the rate of fluid removal from a level of fluid ina canister that stores fluid removed from the wound.
 16. The method ofclaim 15, wherein said monitoring the rate of fluid removal comprisesmonitoring the level of fluid in the canister using one or morecharacteristics of pressure in the fluid flow path.
 17. The method ofclaim 15, wherein said monitoring the rate of fluid removal comprisesmonitoring the level of fluid in the canister from an activity level ofthe negative pressure source.
 18. The method of claim 17, wherein thenegative pressure source comprises a vacuum pump, and the activity levelof the negative pressure source corresponds to a speed of the vacuumpump.
 19. The method of claim 16, wherein the one or morecharacteristics of pressure comprises a magnitude of pressure signals,and wherein the magnitude of pressure signals increases as the level offluid in the canister increases.
 20. The method of claim 10, whereinsaid wirelessly communicating the rate of fluid removal compriseswirelessly communicating the rate of fluid removal to the remote deviceto cause the remote device to store the rate of fluid removal in anelectronic medical record associated with a patient.
 21. The woundtherapy apparatus of claim 1, wherein the controller is programmed tomake the determination within a threshold duration following initiationof treating the wound with negative pressure.
 22. The wound therapyapparatus of claim 1, wherein providing the notification comprisesactivating an alarm.
 23. The wound therapy apparatus of claim 1, whereinthe controller is further programmed to cause the negative pressuresource to decrease a level of negative pressure provided to the wounddressing responsive to the determination.
 24. The wound therapyapparatus of claim 1, wherein the stabilizing structure is configured tocollapse more in a horizontal plane than in a vertical planeperpendicular to the horizontal plane.